A World to Explore

A quick post this week. Above is a bit of a large isotelid trilobite my students and I found this past spring break on an expedition to the Upper Ordovician (Katian) of northern Kentucky. It was collected at a roadside outcrop of the Corryville Formation (Location C/W-740). It doesn’t look like the usual trilobite bit because it is a less common fragment from the underside of the cephalon known as the hypostome (meaning “under mouth”). Note on the left side of the image some branching white encrustations, shown closer below.

These are encrusting cyclostome bryozoans known as Cuffeyella arachnoidea. The genus Cuffeyella was named in 1996 by two characters you know from this blog: Taylor & Wilson. As you can see, these particular specimens are in terrible shape. We have far better images of well-preserved Cuffeyella elsewhere on this blog. One of the lessons of a paleontological education, though, is to learn how to recognize fossils when they are not at their best.

Wooster’s Fossil of the Week is now going to take a hiatus as the summer research and travel season begins. It will return later!

Reference:

Taylor, P.D. and Wilson, M.A. 1996. Cuffeyella, a new bryozoan genus from the Late Ordovician of North America, and its bearing on the origin of the post-Paleozoic cyclostomates, p. 351-360. In: Gordon, D.P., A.M. Smith and J.A. Grant-Mackie (eds.), Bryozoans in Space and Time. Proceedings of the 10th International Bryozoology Conference, Wellington, New Zealand, 1995. National Institute of Water & Atmospheric Research Ltd, Wellington, 442 pages.

Chapel Hill, NC – Every scientist who works in a lab knows that labs have unique characters. The Isotope Geochemistry lab at UNC Chapel Hill was bustling with Ph.D. researchers, graduate students, undergraduate students, and researchers from other institutions, including Appalachian State University and The College of Wooster. We could tell it was a happy lab community by all of the happy faces. The faces weren’t just on the researchers; they were drawn on windows, hoods, and sticky notes. Here are few to brighten your day.

There was a single angry face in the bunch. We called this Samarium Face (Sm-face) because Sm is apparently a finicky element to analyze by mass spectrometry. Maybe someone should make a Sm-face emoji.

Chapel Hill, NC – Whenever we visit a field site or external lab for research, we see it as an opportunity to explore the local culture, in true liberal arts fashion. Our recent visit to UNC Chapel Hill’s Isotope Lab was no exception. We dined on local cuisine at a Chapel Hill barbecue restaurant.

The infamous Duke-UNC rivalry was on display in the last home game for the UNC baseball team. We arrived just as Duke was rallying to come from behind, but in the end, the Tarheels scored a 9-7 victory over Duke.

Friday night, we finished our work just in time to catch a bluegrass band at Carolina Inn’s Fridays on the Front Porch. Although a storm was threatening, it held off so that adults, kids, and dogs could enjoy the outdoor entertainment.

On most days, our walk took us past a UNC Chapel Hill icon: The Old Well. Legend has it that a drink from the Old Well on the first day of classes will bring good luck for the rest of the year.

The highlight of the week was meeting Rameses, the UNC Chapel Hill mascot. Rameses thinks that geologists are #1. He didn’t exactly say so (mascots don’t talk much), but, that’s my interpretation of this photo).

Overall, it was an excellent trip. We learned a new technique, analyzed lots of samples, and acquired data for Ben’s I.S.

Chapel Hill, NC – Wooster Geologists have been hard at work preparing samples for isotope analysis. Now that sample preparation is complete, the next step is to analyze them on the thermal ionization mass spectrometer (TIMS). In the TIMS, a sample heats up until it ionizes, created a beam of charged particles.

The charged particles are sent through a mass spectrometer, which accelerates the ions through a curved path in a magnetic field. The ions separate based on their mass to charge ratio. The separated beams of ions are sent to collectors that convert the ions into an electrical signal that can be used to determine the sample’s isotopic composition. Figure from Revesz et al. (2001).

For a complete overview of how the TIMS works, check out this website at SERC.

Our tiny samples get loaded onto tiny filaments that heat up in the instrument. The filaments are stored in neat, orderly rows in a cabinet in the TIMS lab. If you look closely, you’ll see the flat ribbon onto which we’ll mount our samples.

You can imagine that the filament loading process is as meticulous as the sample preparation work. Here, Ben Kumpf (’18) pipettes a sample onto the filament.

This is what our sample looks like before we heat up the filament. It’s a single drop.

Middletown, CT – The Wooster Geologists at the Keck Consortium were treated to a visit to the Davison Rare Book Room. The Special Collections Librarian set out an impressive array of historical texts with geological significance. We were even permitted to touch the books and turn the pages! Thank you to the Wesleyan Special Collections and Archives for sharing these treasures and allowing us to look through them and take photos.

The 1690 book “Geologia: or, a Discourse Concerning the Earth Before the Deluge” by Erasmus Warren represents an early use of the word ‘geology’ to describe the study of Earth. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Scottish Geologist James Hutton is considered the father of modern geology. In his 1795 two-volume work, “Theory of the Earth,” he argues that Earth is very old and Earth’s features are shaped by natural processes that have occurred over long time scales. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

In the 1800s, Charles Lyell expanded on and popularized Hutton’s ideas. Lyell argued that Earth evolves through small changes that operate continuously over geologic time, a concept known as “uniformitarianism.” Uniformitarianism opposed the prevailing view of catastrophism, in which Earth evolved through a series of catastrophic events. Today, we understand that natural processes have changed the Earth gradually over long time scales, that natural processes can change the rate at which they operate, and that Earth’s history includes occasional catastrophic events. Lyell’s 1839 “Elements of Geology” is a textbook for early geology students. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

This diagram at the front of Lyell’s “Elements of Geology” (1839) shows the relationship between the “four great classes of rocks: aqueous, volcanic, metamorphic, and plutonic.” Today, we combine volcanic and plutonic into the singular igneous category and aqueous rocks are classified as sedimentary. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Lyell’s concept of “uniformitarianism” strongly influenced Darwin, who read Lyell’s work aboard the Beagle. This is a first-edition of Charles Darwin’s famous 1859 work “On the Origin of Species by Means of Natural Selection.” Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Darwin’s book contains personal inscription from the author to his German tutor. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

This “tree of life” figure in Darwin’s “On the Origin of Species” (1859) is the only illustration in the entire text! Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Although Darwin used figures sparingly, paleontologists have long been using images in their publications. This 1854 “Remarks on some Fossil Impressions in the Sandstone Rocks of Connecticut River” by John C. Warren is credited as the first book to use photographs as scientific illustrations. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

The front cover of Warren’s 1854 book contains a salt print of dinosaur tracks. Salt prints were made by soaking the paper in a salt solution then coating one side with silver nitrate. This created light-sensitive paper that darkened in places exposed to light, producing images. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Chapel Hill, NC – As you know, Ben Kumpf (’18) and I are working in the Isotope Geochemistry lab at UNC Chapel Hill. We are measuring isotopes of strontium (Sr), lead (Pb) and neodymium (Nd) in basaltic pillow lavas from northern British Columbia. In order to measure the elements, we need to isolate them from the rest of the elements that make up our rocks. We purify individual elements using the method of column chemistry. A column is like a filter for elements; we pass our sample through the column and the column captures the element of interest, then we release and collect the element off the column to be analyzed later.

The first step to preparing our samples is to dissolve our rock powders in an acid solution. Ben Kumpf (’18) weighs small amounts of rock powder into Teflon vials. We add a series of acids to the vials and let them sit on a hotplate for a day or two until the powders are completely dissolved.

Once the samples are dissolved, we measure out a small amount of the solution into a new vial to run it through the column chemistry process. The first step to make a column “load” solution is to dry the sample solution down to a powder on a hotplate.

To the dried-down powder, we add an acid that is appropriate for the column that we’re using. For Sr, we’re adding nitric acid to the vials.

Now we’re ready to set up the columns. Dr. Ryan Mills (psychedelic lab coat) is showing Ben Kumpf (’18) how to add the resin.

This is what a column looks like up close. It’s suspended above a waste beaker. The white material that is filling the tube and neck is the resin. You can see it still settling out of solution. The resin that we use to isolate Sr was developed in response to the Chernobyl accident when it became necessary to remove radioactive Sr from milk (Vajda and Kim, 2010).

The chemical column process involves adding a series of solutions to the columns in a sequence that cleans the resin, conditions the resin for the sample load solution, introduces the sample, and rinses the sample through the resin. There’s a lot of pipetting and waiting for the solutions to move through the column during this stage.

Samples are centrifuged prior to loading. The centrifuge separates any undissolved solids from the liquid so that we only add the liquid portion to the column.

These columns are loaded with our Pb solutions.

Now that our sample has passed through the column, we release all of the Sr or Pb off of the column and collect it in our sample vial.

The last step in the process is to dry down the sample one final time. This makes a tiny bead at the bottom our vial. We will load this bead into a mass spectrometer to measure the isotope composition.

These beautiful fossils were found in York State Park by Mae Kemsley (’16). It was a surprise gift I found on my doorstep! They are fossil barnacles completely covering the exterior of a valve of the pectenid bivalve Chesapecten middlesexensis (Mansfield, 1936) from the Upper Pliocene. An excellent example of an ancient sclerobiont community.This is the reverse of the specimen, showing the interior of the host shell. Note the large single muscle scar typical of monomyarian pectenid bivalves.Chesapecten is well known among paleontologists. The genus preserves a distinct evolutionary sequence, as seen in the above famous figure from Ward and Blackwelder (1975). This image has been reproduced in countless articles and textbooks.Chesapecten was also the first fossil from North America to be illustrated in a scientific publication. The above image of what we now know as Chesapecten jeffersonius was illustrated in the third volume of Martin Lister’s Historiae Conchyliorum in 1687.Martin Lister FRS (1639 – 1712) was a natural historian and physician born into a prominent family in Radcliffe, England. His father, Sir Martin Lister, was a member of the Long Parliament in the eventful politics of mid-17th century England. He was a nephew of James Temple, a regicide (or patriot, take your choice) and Sir Matthew Lister, physician to Charles I (victim of said regicide). These were just a few of his family connections to politics and science.

Martin Lister was graduated from St John’s College, Cambridge, in 1659, and a year later elected a fellow there. He served as a physician for many years in York, including three years as Queen Anne’s doctor. He became a Fellow of the Royal Society in 1671. He died in Epsom in 1712.

Martin Lister was an extraordinary naturalist, becoming the first conchologist (one who studies shells) and arachnologist (a spider expert). He was a prolific writer, so we know much about what he did, how he worked, and his motivations. He discovered ballooning spiders and invented the ubiquitous histogram. For us his most significant work was Historiae Conchyliorum (1685-1692), which had 1062 plates engraved by his daughters, Anna and Susanna. In keeping with his times, Lister noted the resemblances between fossil and modern shells, but believed the fossils were rocky replicas, not actual remnants of living organisms. He would no doubt be thrilled with our modern views of fossils and evolution.

References:

Kelley, P.H. 1983. The role of within-species differentiation in macroevolution of Chesapeake Group bivalves. Paleobiology 9: 261-268.

Ward, L.W. and Blackwelder, B.W. 1975. Chesapecten, a new genus of Pectinidae (Mollusca, Bivalvia) from the Miocene and Pliocene of eastern North America: USGS Professional Paper 861. US Government Printing Office.

WOOSTER, OHIO — We had the pleasure on Monday of watching our geology seniors cross the stage and receive their diplomas. It happens every year, of course, and every year is special. Above is an image of most of the class taken in September as they started their last year at Wooster.

We were delighted that Wooster Geologist Helen Siegel (’17) earned the opportunity to speak at the commencement ceremony. (Image by ace College photographer Matt Dilyard.) She was a spectacular representation of her graduating class. She earned summa cum laude, Honors in Independent Study, the Jonas O. Notestein Prize, the Phi Beta Kappa Prize, and just about every award offered by the Geology Department itself. She is off to Yale on a full ride. Well done, Helen.

Chapel Hill, NC – Ben Kumpf (’18) and I are at the University of North Carolina at Chapel Hill to use their lab facilities for isotope analysis. We’re working with small amounts of sample and the instrument has a high degree of analytical precision and sensitivity, so all of our sample preparation occurs in the class-1000 clean lab. A clean lab is a room that is specifically designed to limit the amount of airborne contaminants. Special air filters and air distribution systems keep the environment clean so that we can minimize contamination while we separate and purify the isotopes.

Clean labs are classified based on the amounts of specifically sized particles allowed in a cubic meter (~35 cubic feet) of air. If we sample a cubic meter of air in the class-1000 lab and measure the amount of particles that are 5 microns in diameter, we would count no more than 293! For comparison, human hair has a diameter of about 50 to 100 microns, so we’re talking about really tiny bits of airborne dust. Class-1000 refers to Federal Standard 209E, where class-1 is the cleanest space and class-100,000 is the dirtiest (but still pretty darn clean). Federal Standard 209E has been replaced by International Organization for Standardization ISO 14644-1 standards. The new standards include one dirtier and two cleaner classifications and are numbered ISO-1 to ISO-9. Class-1000 is equivalent to ISO-6. UNC Chapel Hill also has a class-100 (ISO-5) clean lab where they process zircons for U-Pb dating.

Before we enter the clean lab, we gear up in the gowning room. The garments are designed to protect the wearer and minimize contamination from the wearer’s body. We wear standard lab safety attire, like glasses, gloves, and a lab coat. We also remove our shoes and exchange them for designated (comfy) slip-on shoes that only go in the clean lab.

Ben Kumpf (’18) went straight from his flight to the lab and is already hard at work. He measured portions of the dissolved samples into new vials so that we can prepare them for Sr isotope analysis. The dissolved samples will be made into solutions that we’ll use tomorrow.

Look for our posts in the following week to learn more about how isotopes are analyzed and what we hope to learn.